Attenuation of Ultraviolet Light by the Lower Atmosphere

Citation

Baum, William Alvin (1950) Attenuation of Ultraviolet Light by the Lower Atmosphere. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/99T9-5S60. https://resolver.caltech.edu/CaltechETD:etd-08272008-082651

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The attenuation of ultraviolet radiation by air near the ground was measured as a function of wavelength under a wide variety of meteorological conditions. These measurements were made over the tops of buildings at the California Institute of Technology on 125 nights between March 1949 and March 1950. Attenuation coefficients in km[...] have been plotted against wavelengths in Angstroms for 78 representative nights. The primary data were obtained from four independent experiments, two which yielded coefficients as a continuous function of wavelength from 2300A to 4600A, and two which monitored coefficients at 2537A and at 5500A. The first method employed photographic spectrophotometry to compare the light transmitted through two paths differing in length by 680 meters. The second method was similar but utilized other apparatus and a path difference of 340 meters. The third method involved mercury lamps and cadmium photocells, and the fourth method consisted of visual observations with a Loofah hazemeter. Except for the Herzberg 02 bands in the neighborhood of 2500A, the attenuation coefficient was found to vary smoothly (though differently) with wavelength on all nights analyzed, including many when smog was present in noticeable concentrations. Attenuation data for unpolluted air were successfully fitted by a simple empirical formula involving wavelength and visibility range as parameters.

Thesis Files